I'm all for saving money, but if the scratches/swirls are really that bad, and the car has been neglected, the only way to remove them is with a ROTARY buffer. They are much more powerful than the ORBITAL buffers, because they generate heat (They spin in a perfect circle and do not oscilate). In the hands of a pro, they are unreal and will remove all swirls. In the hands of an amatuer, you can damage the finish very easily. ORBITAL buffers do not generate heat (since they do oscilate - never sit in the same spot), so damaging your paint ain't gonna happen, unless you use a compound that is not recommended for this purpose.
My advice:
Fork over the doe and get the exterior done by a highly regarded pro that uses a ROTARY buffer - which any Pro worth a nickle uses every day. Expect to spend $100 - ballpark.
Once the car is perfect, you just need to detail once or twice a year with the ORBITAL buffer. This will remove the minor swirls you will obtain from driving, etc... You could learn how to use this no problem, and even used incorrectly will not hurt your paint - assuming you are using a product designed to work with the orbital. Like other have said, purchase the Porter Cable orbital buffer. It is regarded as the best orbital, and many different pads are sold to support your needs.